I'm fixing a sled for my friend and he said he hit a rock and heard a bang and now it doesn't move?i toke the chain case cover off and it had not one drop of oil in it!and it also needs a new chain so that's why it was banging and skipping but then the dip stick was broken and it goes behind the gear? the gears all look fine tho so why is this busted? could there be more damage?